MR. DARWIN ON THE DIMOBPHIC CONDITION IN PRIMULA. 77 
Calanthiun, limited to two Cape species, differs from Pharna- 
ceum as Thylacospermum from Arenaria, by the union of the sepals 
at the base into a campanulate tube, round the edge of which are 
inserted the stamens, being thus much more decidedly perigynous 
than in the rest of the group. 
The genera Psammotrophe, Eckl. & Zeyh., and Polpoda, Presl, 
with uniovulate cells to the ovary, enumerated by Fenzl among 
Molluginez, appear to have nothing to distinguish them from true 
Phytolaecacesm. Adenogramma, Presl, is also a Phytolaccaceous 
plant allied to Giesekia, where the ovary and fruit are reduced toa 
single one-seeded carpel, not compounded of 2 or 3 carpels although 
one-seeded as in Paronychiacesm. Acrossanthes, on the other hand, 
both in habit and character, belongs to the apetalous Ficoidesm. 
IV. PARONYCHIACEE. 
Without having sufficiently examined all the genera of this Order 
to ascertain their limits with respect to each other, or the order 
of their arrangement, we have, however, verified the ordinal cha- 
racters in all the following (except Cardionema) :— 
1. Corrigiola, Linn. (an exceptional genus in its prominent petals 
and alternate leaves); 2. Herniaria, Linn.; 8. Illecebrum, Linn. ; 
4. Cardionema, DC. ; 5. Pentacena, Bartl.; 6. Paronychia, Juss. 
(including Siphonychia, Torr. et Gray, and Anychia, Rich., and 
perhaps altogether, with Cardionema and Pentacena, artificial sec- 
tions of Zllecebrum) ; 7. Habrosia, Fenzl ; 8. Sclerocephalus, Boiss. ; 
9. Gymnocarpos, Forsk. ; 10. Pteranthus, Forsk.; 11. Cometes, 
Burm. ; 12. Dicheranthus, Webb ; 13. Pollichia, Soland. ; 14. Guil- 
leminea, H. B. et K. ; 15. Mniarum, Forst. ; 16. Scleranthus, Linn. ; 
and 17. Lastarriea, A. Gay. 
On the Two Forms, or Dimorphic Condition, in the Species of Pri- 
mula, and on their remarkable Sexual Relations. By CHARLES 
Danwi, M.A., F.R.S., F.LS., &c. 
[Read Nov. 21, 1861.] 
Ir a large number of Primroses or Cowslips (P. vulgaris and veris) 
be gathered, they will be found to consist, in about equal numbers, 
of two forms, obviously differing in the length of their pistils and 
stamens. Florists who cultivate the Polyanthus and Auricula 
are well aware of this difference, and call those which display the 
globular stigma at the mouth of the corolla “ pin-headed ” or “ pin- 
eyed,” and those which display the stamens “thumb-eyed.” I 
